Preliminary studies of blood pressure lowering effect of Nauclea latifolia in rats

Roots of Nauclea latifolia are used in Nigeria for the treatment of hypertension. Ethanolic extract of the root of N. latifolia was administered to anaesthetised rats through the jugular vein while the blood pressure was measured through the carotid artery. The extract reduced systolic, diastolic, and mean arterial pressure in normotensive and in one kidney one clip hypertensive rats in a dose dependant manner. 10 mg/kg of the extract reduced the mean arterial pressure from 115.7 ± 0.4 to 99.6 ± 3.8 mm Hg, while it reduced the systolic and diastolic from 125.6 ± 0.5 to 102.4 ± 4.0 and from 110.5 ± 0.3 to 95.0 ± 3.2 mm Hg respectively. The changes caused in hypertensive rats were much greater. The same dose of the extract reduced the mean arterial pressure from 157.4 ± 4.7 to 72.0 ± 3.6 mm Hg, while it reduced the systolic and diastolic blood pressures from 180.0 ± 5.7 to 90.1 ± 2.6 and from 146.2 ± 3.3 to 63.0 ± 4.9 mm Hg respectively. The extract (10 mg/kg) also reduced the heart rate of normotensive rats from 365 ±12.8 to 280 ± 6.0 beats/min, while it reduced the heart rate of hypertensive rats from 550 ± 22.5 to 120 ± 8.0 beats/min. The reduction in blood pressure and heart rate was not affected by prior treatment with atropine or promethazine.   Key words: Blood pressure, Nauclea latifolia root, phytochemical.